IP Multimedia services provide a dynamic combination of voice, video, messaging, data, etc. within the same session. By growing the number of basic applications and the media which it is possible to combine, the number of services offered to the end subscribers will grow, and the inter-personal communication experience will be enriched. This will lead to a new generation of personalised, rich multimedia communication services, including so-called “combinational IP Multimedia” services.
IP Multimedia Subsystem (IMS) is the technology defined by the Third Generation Partnership Project (3GPP) and ETSI TISPAN group to provide IP Multimedia services over mobile communication networks. IMS provides key features to enrich the end-subscriber person-to-person communication experience through the use of standardised IMS Service Enablers, which facilitate new rich person-to-person (client-to-client) communication services as well as person-to-content (client-to-server) services over IP-based networks. The IMS makes use of the Session Initiation Protocol (SIP) to set up and control calls or sessions between subscriber terminals (or subscriber terminals and application servers). The Session Description Protocol (SDP), carried by SIP signalling, is used to describe and negotiate the media components of the session. Whilst SIP was created as a subscriber-to-subscriber protocol, IMS allows operators and service providers to control subscriber access to services and to charge subscribers accordingly.
By way of example, FIG. 1 illustrates schematically how the IMS fits into the mobile network architecture in the case of a GPRS/PS access network (IMS can of course operate over other access networks). Call/Session Control Functions (CSCFs) operate as SIP proxies within the IMS. The 3GPP architecture defines three types of CSCFs: the Proxy CSCF (P-CSCF) which is the first point of contact within the IMS for a SIP terminal; the Serving CSCF (S-CSCF) which provides services to the subscriber that the subscriber is subscribed to; and the Interrogating CSCF (I-CSCF) whose role is to identify the correct S-CSCF and to forward to that S-CSCF a request received from a SIP terminal via a P-CSCF.
Within the IMS service network, Application Servers (ass) are provided for implementing IMS service functionality. ASs provide services to end users in an IMS system, and may be connected either as end-points over the 3GPP defined Mr interface, or “linked in” by an S-CSCF over the 3GPP defined ISC interface. In the latter case, Initial Filter Criteria (IFC) are used by an S-CSCF to determine which Ass should be “linked in” during a SIP Session establishment (or indeed for the purpose of any SIP method, session or non-session related). The IFCs are received by the S-CSCF from a home subscriber server (HSS) during the IMS registration procedure as part of a user's or subscriber's Subscriber Profile.
A user equipment may comprise or represent any device used for communications. Examples of UE that may be used in certain embodiments of the described network(s) are wireless devices such as mobile phones, terminals, smart phones, portable computing devices such as lap tops, handheld devices, tablets, net books, computers, personal digital assistants and other wireless communication devices, or wired communication devices such as telephones, computing devices such as desktop computers, set-top boxes, and other fixed communication devices.
A network element may comprise or represent any network node, device, function, or entity in a telecommunications network for use in allowing a UE access to the network. Examples of network elements that may be used in certain embodiments of the described network(s) are network elements, nodes, devices, functions, or entities that make up core network(s), access network(s) such as packet or circuit switched network(s), IP based networks, 2G, 3G, 4G and next generation networks, IMS core network, IMS service network, and service and external networks and the like. Other examples include the network elements such as those illustrated in FIG. 1.
A trace session is a communications session in which a test call is made to determine where a network problem may exist within a telecommunications network. For example, a customer support helpdesk or a field technician may use a UE, e.g. UE A, to initiate a trace session with the UE of a user or subscriber, e.g. UE-B, in which the network trace is configured to trigger selected network elements and the associated UEs to send trace results to a trace collection entity for analysis. There are several types of activation methods available for performing network troubleshooting such as management activated or signalling activated trace sessions. There are also several types of trace sessions such as Net Trace and SIP trace sessions.
The 3GPP Technical Standards 32.421, 32.422, and 32.423 provide guidance for current trace sessions for use in tracing problems within a telecommunications network including an IMS network. In particular, TS 32.421 describes subscriber and equipment trace concepts and requirements, TS 32.422 describes subscriber and equipment trace control and configuration management, and TS 32.423 describes subscriber and equipment trace data definition and management. The current procedures include initiating a trace session via management activation or signalling activation, which is described in TS 32.422.
A management activation trace session requires interaction with all selected network or node elements, in which each network element requires memory to store the trace results for the duration of the trace session. The trace results include data representative of traffic data from the call established during the trace session. In addition, this type of activation method is non-standardised, and may require different procedures for operating network elements from different vendors.
A signalling activation trace session activates a trace per subscriber in the HSS. The trace session may only be activated when a UE re-registers with the network. Propagation to each network element is performed at re-registration resulting in a slow procedure for retrieving trace results. This type of activation method requires additional central processing power in the HSS and within the network elements and requires additional memory for storing the trace results during the trace session.
As described above, management activation network trace procedures require interaction with each network element or node in the network. Signalling activation network trace activation is done well in time before a test call is made. Signalling activation also requires that the AS uses third party re-registrations and typically queries the HSS for each re-register to determine if the network trace status has changed since the last re-registration. These re-registrations to the AS and the need for Sh lookup in the HSS require a large amount of central processing power. In addition, is it not possible to know when, for example, the AS will have the new network trace status because of the long time (e.g. hours) between each re-registration.
There is a desire to have the ability to place test calls in the telecommunications network to determine whether and where a network problem may exist, even all the way to the UE without actually making the UE ring. There is also a desire as a customer support helpdesk or field technician to activate network trace dynamically to get instant trace results in the telecommunications network. There is also a desire for a customer support helpdesk or field technician to perform trace calls without disturbing the end user, while getting network information from all nodes and the terminating UE.